FR2580764A1 - HIGH PRESSURE SEALING DEVICE BETWEEN TWO RELATIVE MOTION ELEMENTS - Google Patents

Abstract

SEALING DEVICE INCLUDING TWO SEALING ASSEMBLIES 36, 37 SPACED FROM ONE OF THE OTHER, LIKELY TO MOVE AXIALLY IN A CHAMBER 14 CIRCUMVISORY OF THE DIVER 3, THE SPACE INCLUDED BETWEEN THE SAID ASSEMBLIES BEING FILLED WITH A FLUID D 'WATERPROOFING. A SEALING ASSEMBLY IS IN THE FORM OF AT LEAST TWO RINGS: AN EXTERIOR RING 38, 48 WITH AN EXTERIOR CYLINDRICAL SURFACE AND AN INTERNAL TAPERED SURFACE, AND AN INTERNAL RING 39, 49 WITH AN INTERNAL CYLINDRICAL SURFACE AND AN EXTERIOR TAPERED SURFACE TWO RINGS, CONCENTRIC, BEING AT LEAST PARTIALLY NITCHED ALONG THEIR CONICAL SURFACES. THE RINGS SHOW ON THEIR RADIAL SURFACES AT LEAST ONE THROAT 40, 41, 50 IN WHICH IS LOCATED A SEAL 44, 45, 51.

Description

The invention relates to a high-pressure sealing device between two

  relatively moving elements, more particularly for a pump or a pressure amplifier comprising a plunger moving longitudinally reciprocating in a chamber for compressing under high pressure a fluid introduced therein. It is known, for example, from French Patent No. 2 182 519 a sealing device, for a pump or a pressure amplifier, disposed between the surface of the plunger and the liner of a chamber formed in the cylindrical body of a pump. . The device, housed in the liner, comprises a segment communicating with the external sealing fluid supply circuit. On the radial walls of the segment rests a ring whose

  second side face has a convex shape.

  This face cooperates with chevron sealing rings. The last ring comes into contact with an outer ring whose adjacent face is complementary to the chevron ring and whose other face comes against a bearing ring in contact with

  the radial wall of the plunger guide sleeve.

  The tightening of the ring and segment assembly is obtained by a nut screwed into the cylindrical body. The sealing fluid is introduced by the segment under a pressure corresponding to that which prevails in the pump chamber during the compression cycles and passes between the sealing rings and the surfaces of the piston and the jacket towards the end. at lower pressure. The leakage fluid is recovered in an annular space at atmospheric pressure. The leakage of the sealing fluid is determined by the tightening of the rings which must be

  frequently readjusted as a result of wear.

  French Patent No. 2 155 531 discloses a pneumatic spring sealing device comprising, between the inner surface of the cylinder and the piston, two sealing rings, separated by a space filled with a sealing fluid. The two rings have, on their lateral faces facing the outer and inner lips. On the side of the atmosphere, the first ring rests against a fixed end piece. On the high pressure side, the second ring rests against a radial face of a mobile end ring whose other face is subjected to the high pressure of the gas enclosed in the cylinder. As a result of the differences in the cross-section of the end ring and the sealing rings, a pressure greater than that of the gas is exerted on the sealing fluid which sets the lips of the rings against the walls of the cylinder.

and the piston.

  The main function of this seal is to prevent leakage of swelling compressed gas

  permanently the air spring.

  French Patent No. 2,225,043 discloses a reciprocating pump for high pressures which comprises a seal consisting of a floating piston capable of moving in a sealed manner in an annular chamber. One face of the piston is subjected to the high-pressure fluid which escapes between the walls of the jacket and the piston of the pump during the ompression stroke, the floating piston is then pushed back and compresses the fluid of its other face. sealing, which is introduced during the intake stroke in a chamber located on the low pressure side. The sealing fluid, discharged between the jacket and the piston towards the low pressure, is recovered and

  returned to the supply circuit.

  The seal thus produced is satisfactory by means of a large fluid leak. In addition, the seals sealing between the high pressure liquid and the fluid are subject to significant wear and require frequent changes if you want

avoid a drop in efficiency.

  The invention relates to a device similar to those mentioned above, but proposes to provide a sealing device having a minimal leakage of the sealing fluid and having sealing rings to catch games with an efficiency increased and a more

great longevity.

  The device according to the invention is remarkable in that at least one of said sealing assemblies is formed of at least two rings: an outer ring having an outer cylindrical surface and an inner conical surface, and an inner ring having a surface inner cylindrical and outer conical surface, the two concentric rings being at least partially encased along their conical surfaces. the explanations and figures given below as examples will help

  understand how the invention can be realized.

  FIG. 1 represents a schematic section of a high pressure pump comprising a first embodiment of a device

sealing according to the invention.

  FIG. 2 is a sectional view on a larger scale of the sealing device

of Figure 1.

  FIG. 3 is a diagrammatic section of a high pressure pump comprising a second

  exemplary embodiment of a sealing device.

  FIG. 4 is a sectional view on a larger scale of the sealing device of the

figure 3.

  FIGS. 5 to 8 show other exemplary embodiments of sealing devices

according to the invention.

  FIG. 1 represents, in schematic section, a high-pressure pump or a pressure booster comprising a sealing device according to an exemplary embodiment

of the invention.

In the rest of the description,

  designate the general term pump, high-pressure pumps, pressure amplifiers and other devices capable of producing high pressures through the stroke of a

piston or plunger.

  The pump consists of a cylindrical assembly comprising: a cylindrical casing 1 mounted, at one of its ends, on the motor device whose output member 2 transmits to the plunger 3 a reciprocating movement; - A body 4 fixed by a connecting flange 6 to a corresponding connecting flange 7 provided at the other end of the housing. The body is traversed axially by a bore in which is housed a sleeve 8 of relatively small thickness in which the plunger 3 moves. Channels 9 and 10 communicate the bore and the radial face 11 of the body respectively with the provided orifices. on the outer surface; a cover 5 fixed to the end of the body, carrying along its axis a bore 12 forming a pressure chamber; - A sleeve 13 extending the bore and whose inner diameter is equal to that of the bore and the sleeve 8, one end of the sleeve protruding from the radial face of the cover to be housed in a bore of the body provided in the extension of the shirt 8; a sealing chamber 14, concentric with the sleeve and communicating via a channel 16 with a feed chamber 15 provided in

the thickness of the lid.

  The bottom of the pressure chamber 12 communicates with a purge channel 17 and a

  pipe 18 for admission of the pressure fluid.

  The lid 5 is attached to the body

  in known manner by bolts 19.

  The sealing device, according to the invention, consists of the sealing chamber 14 and two sealing assemblies 20, 21 disposed on either side of the opening of the channel 16

  intake of the sealing fluid.

  According to the embodiment shown in FIG. 2, at least one sealing assembly, for example the assembly 21, consists of two rings: an outer ring 22, whose cylindrical outer surface is able to cooperate directly or indirectly in a sealed manner with the outer wall of the chamber 14 and an inner ring 23 whose cylindrical inner surface is able to cooperate directly or indirectly sealingly with the inner wall of the chamber 14 constituted in this

  for example, by the outer surface of the sleeve 13.

  The terms "outside and inside" are used to refer to relative positions

  relative to the axis of the pressure chamber.

  Outdoor means': the furthest position

  of the axis and inner nearest.

  The two rings, concentric, are at least partially nested along two cooperating conical surfaces 241, 242. Preferably, the inner ring 23 has a section in the form of a right-angled triangle whose large side is directed against the outer surface of the sleeve 13, and the outer ring 22, a rectangular trapezoid-shaped section whose height is directed against the inner wall of the sealing chamber 14, the large base of the trapezoid being approximately

  equal to the height of the sealing chamber.

  The outer ring 22 carries on its periphery a groove 25 in which is housed a

O-ring 26, elastic.

  The assembly 21 seals the low pressure side corresponding to the inlet of the plunger in the bore of the pump body, while the assembly 20 ensures the tightness of the high side.

  pressure corresponding to the pressure chamber 12.

  According to a simplified embodiment of the assembly 20, more particularly adapted to the case where one sends in the sealing chamber a fluid at a pressure corresponding to that produced in the pressure chamber 12, this set consists of a ring made of a plastic material of rectangular section, separated from the end of the sealing chamber by a ring

anti-extrusion 27.

  In the example shown in FIG. 1 and in particular in the large-scale detail view of FIG. 2, the sealing chamber 14 is at least partially occupied by an elastic member 28 in the axial direction and whose ends support against the big

  bases of the upper rings 22, 22 '.

  The chamber 14 is in communication with an external pump which, during operation, delivers a pressure identical to that which prevails in the pressure chamber 12. The sleeve 13 is made of a deformable material, for example a bronze, present in its central portion and on its inner face, a groove 29 provided with orifices 30 opening into the sealing chamber 14. The sleeve further has, on the high pressure side, a groove 31 intended to receive a separating seal 32 which prevents any leakage of sealing fluid to the high pressure circuit 12. In contrast, is provided an expansion groove 33 whose width is adjusted to limit the contact surface between the sleeve

13 and the diver 3.

  During operation, the pressure generated in the pressure chamber 12 is transmitted to the sleeve 13 via an external pump, which has the effect of catching the initial diametral clearance between the sleeve and the plunger and to ensure sealing at this level. In addition, the pressure of the sealing fluid is applied to the assemblies 20 t 21 and in particular to the large base of the outer rings 22 and 22 'which act as pistons and tend, through the conical surface to close the rings. 23, 23 'on the sleeve 13 and thus provide sealing. Thin inner rings are usually machined from a deformable material, such as bronze, so that they can deform under the action of thicker outer rings.

which are, for example, steel.

  During the return stroke of the plunger during the admission phase of the pressure fluid into the pressure chamber 12, the outer rings are no longer subjected to pressure and tend to return to their original dimensions leaving a relatively large clearance between the outer wall of the sealing chamber 14 and the surface of the ring opposite, the seal 26 then ensures sealing with the low pressure side. To maintain the seal 26 against the wall of the chamber, the displacement of the outer ring 22 is limited by the elastic member 28, which permanently applies a relatively low value pressure to the ring 22 taking

  bearing against the other sealing assembly 20.

  The elastic member is constituted for example by a ferrule pierced with radial and axial channels to allow the passage of the sealing fluid, or by a system of rings held by springs.

  or by any other elastic element.

  Under the high pressures generated, the sealing device may show fluid leaks between the cooperating faces of the body and the lid, between the liner and the plunger and between the liner and the body. The leakage fluid is recovered in grooves 34 and 35 which are communicated with the feed system

  in sealing fluid through the channels 9 and 10.

  According to another embodiment of the invention, shown schematically in FIG. 3, the sealing chamber is not supplied with sealing fluid by an external pump. According to one characteristic of the invention, the pressure is transmitted to the fluid of the chamber by one of the sealing assemblies acting as a piston and whose face turned towards the high pressure withstands at each compression stroke the pressure generated in the chamber. pressure 12, pressure transmitted by the passage of the pressure liquid between the

  plunger 3 and the bottom of the sealing chamber 14.

  In FIGS. 3 and following elements similar to those previously described

bear the same references.

  According to the example of Figures 3 and 4, the sealing chamber 14 opens directly into the axial bore provided in the cover 5 and in the extension of the sleeve 8 housed in an axial bore of the body. Sealing assemblies 36, 37

  are in direct contact with the diver 3.

  The sealing assembly 36, disposed on the high-pressure side, consists of two rings: an outer ring 38 and an inner ring 39, coaxial, nested according to two conical surfaces facing each other. Both rings are approximately triangular section and

  have on their radial side a semi-

  40 and 41 tangent to the conical surface of the other ring while the end of the conical surface of the ring carrying the housing has a bead 42, 43 whose conical surface to the conical surface has in a diametral plane a radius of curvature equal to that of the toroldal housing. When the two rings are mounted one inside the other, the housings 40, 41 and

  the beads 42, 43 form semicircular grooves

  toric, whose input is narrowed, in which are housed two O-rings 44, 45 of elastomer. These seals make the two rings integral for mounting and also seal the continuity solution between the two conical surfaces. Each of the rings bears on the cylindrical face a groove 46, 47 which

  receives a circumferential seal.

  The angle that conical surfaces make, relative to

  to the axis of the chamber 14, is of the order of 25.

  the sealing assembly 37, disposed on the low pressure side, is formed of an outer ring 48 and an inner ring 49; The outer ring 48 has a section of triangular shape and cooperates with one of its sides with the outer surface of the chamber 14 and carries a circular groove 55 in which is housed an O-ring. A second side forms the conical surface cooperating with the corresponding conical surface of the inner ring. The third side has a circular groove 50 forming a

  housing portion for an O - ring 51.

  The inner ring 49, also of triangular section, cooperates with two of its perpendicular sides 52, 53 respectively with the radial end of the jacket 8 and with the surface of the plunger 3. Thirdly, a conical surface forms, forming an angle of 650 with the axis of the chamber, connecting with a portion approximately parallel to the side 53 by a toroidal surface forming the other part of the housing of the O-ring 51 and determining

  a bead 54 on the edge of the ring 49.

  The outer 48 and inner 49 rings are secured by the O-ring 51, which

  is maintained at the bottom of the groove by the bead 54.

  In a simplified manner, a sealing assembly, according to the invention, can be defined as a cylindrical assembly formed of two conical rings, the section of the assembly being approximately in the form of a rectangle cut along a diagonal , and having on at least one of its radial faces a circular groove housing an elastic O-ring, the groove formed in one of the rings being tangent

  to the conical surface of the other ring.

  The mode of operation of the sealing device according to the embodiment described above is as follows: during the compression stroke, the plunger 3 moving towards the bottom of the pressure chamber 12 compresses the pressure fluid which introduced between the surface of the plunger and the wall of the pressure chamber to the bottom of the sealing chamber 14 where it pushes the seal assembly 36 to the low pressure side. The sealing fluid that fills the chamber 14 under normal pressure is subjected by the assembly 36 to the high pressure that it transmits to the assembly 37 ensuring the tightness of the low pressibon side. The pressure acting through the O-ring on the outer ring 48 tends to cancel the initial play and strongly press this ring against the outer surface of the chamber and secondly against the inner ring 49 via the conical scope. An identical process applies to the inner ring 49 which bears on the plunger 3 and seals at this level. A slight leakage of the sealing fluid is tolerated and participates in the lubrication of the plunger thus improving the

  friction and the life of moving parts.

  During the suction stroke, the plunger moves to the low pressure side, the pressure in the pressure chamber falls and the assembly 36, which is no longer pushed by the pressure fluid, returns to its initial position, to the bottom of the sealing chamber of the high-pressure side, pushed back by the sealing fluid. The stress which was exerted against the whole 37 of the low pressure side ceases. Sealing is ensured, both on the low pressure and high pressure side, by the O-rings that equip the grooves 55, 46 and 47. As leakage of sealing fluid is admitted and there is no continuous supply of the chamber 14, it is provided on the inner ring 39 of the assembly 36 placed on the high pressure side, a flange 56, directed towards the low pressure side, acting as a stop to maintain a minimum distance against the two assemblies for intermittent compensation of leakage

sealing fluid.

  According to another exemplary embodiment, according to the invention, shown in FIG. 5, the sealing assembly 37, placed on the low pressure side, is identical to that previously described, while the assembly 57, placed on the high pressure side. , comprises two outer rings 58, 59 and an inner ring, having a cylindrical portion 61 carrying at its periphery and approximately in the radial plane

  of symmetry a trapezoidal collar 62.

  the outer rings 58 and 59 are in all respects similar to the outer ring 48 of the sealing assembly 37 placed on the low pressure side. The assembly 57 can be considered as formed of two integral sealing assemblies 37 arranged symmetrically with respect to a

radial plane.

  As in the assemblies previously described, the rings are secured by means of the O-rings 63, 64 held in grooves of appropriate geometry. The operating principle of the sealing assembly is similar, by the outer ring 59 and the inner ring. 60 to that of the assembly 37: the pressure transmitted by the O-rings acts on the rings, causes the catch of the games and ensures a contact of these elements in

  the bore of the sealing chamber.

  Another embodiment of a sealing assembly is shown in FIG. 6. The sealing assembly 37, on the low pressure side, is identical to the corresponding assembly of the previous embodiments. The sealing assembly 65 on the high-pressure side comprises a central ring 66 having a straight S-shaped section, flattened, comprising two cylindrical portions 68, 67 cooperating respectively with the outer surface of the chamber 14 and with the surface of the plunger 3, connected by an oblique portion 69 forming with the two parts 68, 67 an angle greater than 90 (for example 115) and two rings 70, 71 respectively outer and inner, having as the outer ring 48 of the assembly 37 a conical surface cooperating with the conical surfaces formed by the oblique portion 69 of the ring 66, said rings being arranged symmetrically with respect to

at the ring 66.

  The operating mode of the sealing assembly 65 is in all respects comparable to that of the assembly 37 depending on whether the pressure is exerted on the high pressure side or on the side

low pressure.

  In the embodiment shown, the sealing chamber 14 is closed. The sealing fluid is introduced through a pipe 72 opening upstream of the sealing assembly 37 placed on the low pressure side, in a chamber 73. During the intake cycle of the pressure fluid, the assembly 37 is more subject to high pressure and it is then possible by sending the relatively low pressure sealing fluid (for example 100 bar) to move the inner ring 49 away from the surface of the plunger, to make it penetrate into the chamber o it compensates for

  possible losses due to leaks.

  FIG. 7 shows an example of a sealing device in which the sealing fluid filling the chamber 14 is a pasty product consisting for example of a binder loaded with teflon particles or any other suitable material whose particle size will be chosen according to of

type of employment envisaged.

  FIG. 8 shows a sealing device similar to that of the previous example in which an abutment ring 74 is placed against the bottom of the sealing chamber, on the high pressure side, to prevent jamming of the Ring

  outer 38 of the sealing assembly 36.

  The chamber 14 being subjected to high pressures, for example of the order of 2000 to 3000 bar, machining with acute angles can not be accepted, because these are the seat of a stress concentration facilitating corrosion, and entralnant the breaking of the piece. In order to avoid this drawback, the bottom of the chamber has a connection curve which requires either a particular machining of the edge of the outer ring.

  as shown in Figure 4 et seq.

position of an abutment ring.

  The advantages of the sealing device according to the invention are: - the integration of all the sealing assemblies in the cover so as to keep only one element urged under pressure; - the simplification of the jacket and the removal of the constraints related to the high pressure; the possibility of surface hardening treatments of the sealing chamber, as a result of its position in the lid, making it possible to increase the hardness of the chamber and consequently to obtain a better seal and a more long life; - the simplification of machining; - the quality of the seal and the longer service life than those obtained with the

device of the prior art.

  the arrangement of the rings enables them to work only in compression and not in flexion with catching up of the games thanks to their

c8ne movement on c8ne.

Claims (12)

  High pressure sealing device between two elements in relative movement, more particularly intended for a pump or a pressure amplifier, comprising a plunger moving longitudinally reciprocatingly in a pressure chamber for compressing a fluid contained in said plunger chamber being surrounded by a sealing device comprising two sealing assemblies spaced from one another, capable of moving axially in a chamber around the plunger, the space between said sets being filled with a sealing fluid, characterized in that at least one of said sealing assemblies is formed of at least two rings: an outer ring (21, 38, 48) having an outer cylindrical surface and an inner conical surface, and a inner ring (23, 39, 49) having an inner cylindrical surface and an outer conical surface, the two rings, concentric, at least partially embossed along their conical surfaces.   2. Device according to claim 1, characterized in that the outer ring (22, 38, 48, 59, 67) carries on its cylindrical surface a groove (25, 46, 55) in which is housed an elastic seal. 3. Device according to claim 2, characterized in that the inner ring (39, 61, 71) carries on its eylindrical surface a groove (47)   in which is housed an elastic seal.   4. Device according to claim 1, characterized in that the sealing assembly forms a cylindrical assembly consisting of at least two conical rings (21, 23; 38, 39; 48, 49), the section of the assembly. approximately in the form of a rectangle cut diagonally and having on at least one of its radial faces a circular groove (40, 41, 50) in which an elastic O-ring (44, 51; 64), said groove formed in one of the rings being tangent to the conical surface of the other ring.   5. Device according to claim 4, characterized in that the end of the conical surface of the ring to which the seal is tangent comprises a bead (42, 54) forming a narrowing at the entrance of the groove to maintain gasket.   6. Device according to claim 1, characterized in that at least one sealing assembly (57) is formed of two sets as described, integral, arranged symmetrically with respect to the radial plane, said assembly comprising two outer rings (58). , 59) and an inner ring (60), said inner ring having an inner cylindrical portion (61) bearing at its periphery and approximately in the radial plane of symmetry, a trapezoidal collar (62). 7. Device according to claim 1, characterized in that at least one sealing assembly comprises a central ring (66) of flat S-shaped section, flattened, having two cylindrical surfaces (68, 67) cooperating respectively with the outer surface of the sealing chamber (14) and with the plunger (3), connected by an oblique portion (69) forming with the two cylindrical portions an angle greater than 90, and two rings: an outer (70) and a interior (71) having a conical surface cooperating with the conical surfaces formed by the oblique portion (69) of the central ring (66), and arranged symmetrically by relative to the central ring (66). 8. Device according to one of   preceding claims having two sets   sealing, an assembly being on the low side   pressure and the other side of the high-pressure   in that the sealing assembly (36, 57) placed on the high pressure side has on the inner ring (39, 60) a flange (56) directed towards the low pressure side acting as a stop to maintain a minimum spacing between the two sealing assemblies. 9. Device according to one of the   Claims 1 to 7, characterized in that   elastic member (28) is provided in the sealing chamber (14) for permanently applying pressure against at least the sealing assembly   (21) located on the low pressure side.   10. Device according to claim 1, characterized in that the inner ring (s) (23) of the sealing assemblies (20, 21) cooperate by their inner surface with a deformable sleeve (13) provided around a portion of the plunger. (3). 11. Device according to one of the   preceding claims, characterized in that   the sealing assembly (36, 57, 65) located on the high pressure side transmits by its radial face located on the high pressure side, said pressure to the sealing fluid occupying the space between said two sets. 12. Device according to one of the   preceding claims, characterized in that   the rings are metallic, for example bronze   and rubber or elastomer seals.